Answer:
If length of the field is 30 ft, then width is 120 ft.
If the  length of the field is 60 ft, then width is 60 ft.
Step-by-step explanation:
Let us assume the length of the rectangular park = L ft
Let us assume the breadth of the rectangular park = B Â ft
Now, AREA of the given park = Â L x B
⇒ L x B  = 3,600 sq ft  ... (1)
Also, the perimeter of three sides  = 180 ft
⇒ 2 L +  B  = 180  ..... (2)
Now, from (1) and (2), we get:
L x B Â = 3,600
2 L +  B  = 180  ⇒ B  = 180 - 2 L
Substitute this in(1) , we get:
L x B  = 3,600  ⇒ L x (180 - 2 L)  = 3600
[tex]\implies 180 L - 2L^2 = 3600\\\implies L^2 -90L + 1800 = 0\\\implies (L-30)(L-60)= 0[/tex]
⇒ L = 30 or L  = 60
So, if L Â = 30 Â ft , then B = 180 - 2L Â = Â 180 - 60 = 120 ft
So, if L Â = 60 Â ft , then B = 180 - 2L Â = Â 180 - 120 = 60 ft
So, if length of the field is 30 ft, then width is 120 ft.
And if the  length of the field is 60 ft, then width is 60 ft.